There is conventionally known a trunking type wireless communication system (hereinafter, referred to as a “trunking system”) as a business land mobile wireless communication system. In a trunking system, a predetermined number of repeaters are present in a site, and a plurality of wireless terminal devices shear a predetermined number of communication channels through the predetermined number of repeaters. The trunking system includes a dedicated control type having a dedicated control channel and a distributed control type having no dedicated control channel. Based on control information from the control channel in the case of the former type and based on control information from a home repeater registered in each wireless terminal device beforehand in the case of the latter type, an unused communication channel is set to allow the wireless terminal devices to communicate with each other, so that the plurality of wireless terminal devices shear the predetermined number of communication channels. One of the plurality of repeaters functions as a master repeater, and the others function as slave repeaters, respectively. The slave repeater operates in synchronization with a synchronization signal output by the master repeater.
In this case, if individual repeaters output a synchronization signal on a communication line without any permission, it becomes difficult to establish a synchronization because of collision of such synchronization signals. Accordingly, only a specific repeater (which is called a “master repeater”) selected from the plurality of repeaters outputs a synchronization signal to the communication line, other repeaters (which are called “slave repeaters”) acquire a timing of information on a system bus in synchronization with the synchronization signal output by the master repeater. If a master repeater breaks down due to some reasons, it is necessary to select a new master repeater in the remaining slave repeaters.
For example, patent literature 1 discloses a technology which connects a master repeater and a plurality of slave repeaters one another over a system bus, and which automatically changes the master repeater to a new master repeater when the master repeater that outputs a synchronization signal breaks down. The master repeater generates a synchronization signal based on a reference signal output by a VCXO (an oscillator circuit), and outputs the generated synchronization signal to the plurality of other slave repeaters. Each repeater is connected to another repeater through a synchronization signal connector in order to transmit/receive the synchronization signal, and is connected to another repeater through an Ethernet (registered trademark) for a LAN connection for a control communication relating to a connection of a communication channel.
Patent literature 1 discloses that when it is determined that the master repeater outputting the synchronization signal breaks down, a main CPU of each slave repeater establishes a communication with another repeater through the Ethernet (registered trademark) for a LAN connection, and a relationship whether another repeater is the master repeater or a slave repeater at the time of breakdown.    Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. 2007-281800